pearlite
A close-up diagram shows the lamellar structure of pearlite in a polished steel sample.
Noun 1. A specific microstructure in iron-carbon alloys: Pearlite is a lamellar (layered or plate-like) mixture of two distinct phases: cementite (iron carbide, Fe₃C) and ferrite (almost pure iron). It forms when austenite (a high-temperature solid solution of carbon in iron) cools slowly. Pearlite is a fundamental and common constituent of steel and cast iron, contributing to their strength and hardness.
- The metallurgist examined the sample under the microscope and identified the fine pearlite structure.
- The strength of this grade of steel is derived from its pearlite content.
- Slow cooling promotes the formation of coarse pearlite.
- Pearlite colonies: Groups of pearlite nodules that share the same orientation of their lamellae.
- Interlamellar spacing: The distance between the cementite plates within the pearlite; a finer spacing generally increases strength.
- Spheroidized pearlite: A heat-treated condition where the cementite lamellae transform into spherical particles within the ferrite matrix, improving machinability.
- Pearlitic (adjective): Describing a material or structure containing or resembling pearlite.
- The steel had a fully pearlitic microstructure.
- Cementite: The hard, brittle iron-carbide phase (Fe₃C) in pearlite.
- Ferrite: The soft, ductile, body-centered cubic iron phase in pearlite.
- Austenite: The high-temperature face-centered cubic phase of iron that transforms into pearlite upon cooling.
- Lamellar ferrite-cementite aggregate (technical description)
Pearlite is a specific term in metallurgy and materials science. It refers exclusively to the two-phase, lamellar microstructure found in ferrous alloys (iron and steel). It is not a standalone material but a constituent within a metal's microstructure.
A close-up diagram shows the lamellar structure of pearlite in a polished steel sample.
- a lamellar mixture of cementite and ferrite formed during the cooling of austenite; a constituent of steel and cast iron